Method and apparatus for forming cores



Sept. 15, 1959 D. C. CAUDRON METHOD AND APPARATUS FOR FORMING COREIS Filed Sept. 18, 1957 INVENTOR.

Donald C. Cauc/ron EC/(HOFF SLICK ATTORNEYS 2a 4 A MEMBER OF THE F United States Patent METHOD AND APPARATUS FOR FORMING CORES Donald C. Caudron, Berkeley, Calif.

Application September 18, 1957, Serial No. 684,686

4 Claims. (Cl. 22-192) This invention relates to the formation of cores and particularly to a novel method and apparatus for the rapid formation of cores at low cost.

It is in general the broad object of the present invention to provide a new method for the manufacture of cores.

Another object of the present invention is to provide a novel apparatus for the formation of cores.

The invention includes other objects and features of advantage, some of which, together with the foregoing,

will appear hereinafter wherein the present preferred form of practicing the invention is set forth in conjunction with the novel form of apparatus, the latter being shown more or less schematically in the drawing. Referring to the drawing, the several Figures 1 through 4 represent sections taken through a core box and associated apparatus, showing various steps in manufacture of a core in accordance with this invention.

Referring particularly to Figure l, a base, generally indicated at 6, is provided which serves as a support for any suitable core box 7. The core box is mounted upon a cooperatingly formed boss 8 on top of the base 6, to permit of the ready removal of the core box 7 and its contained core when the core is completed.

Means are provided for mounting a tubular member 9 on the base, such member being made of a flexible material such as rubber or the like. The seal means comprises an aperture 11, through which the tubular member is passed in tight engagement with the wall defining the aperture 11 having an annular recess 12 therein. Immediately beneath the recess 11 an enlarged cavity 13 is provided, the latter having a resilient annular ring 14 engaging the bottom of the cavity and having an annular sidewall 16 which fits the tubular resilient member 9. Cavity 13 is connected with an inlet 17 and the tubular member 9 opens into cavity 13 so that gas under pressure can be forced into the tubular member.

To manufacture a core, referring more particularly to Figures 2 and 3, the tubular member 9 being in position and at a desired elevation within the core box, a suitable moulding composition, generally indicated at 21, is placed in the core box. The cover 22 is then secured in position over the top of the core box to provide an enclosure.

The molding composition generally comprises a suitable sand or like finely divided material wet with a suitable sodium silicate. In place of sodium silicate, one can use other cold quick-setting liquids such as an oil containing an accelerator which, upon application of air or oxygen, causes the oil to set up and harden. Such compositions have the inherent property of setting up upon application of a gas such as carbon dioxide, oxygen or air; these compositions are well-known in the coreforming art and need not be described further.

In accordance with this invention, carbon dioxide is used simultaneously to compact the core and set up the core by reaction with the silicate present in the sand.

To enable the carbon dioxide to compact the molding 2,903,762 Patented Sept. 15, 1959 ice sand in the core box 7 and to set up the sand as a core of adequate strength, the tubular member 9 is provided with several restricted passages 24 in the side wall thereof such as are made by pressing the point of a fine sewing needle through the side wall of the member. Upon application of carbon dioxide under the pressure of the order of 50150 pounds through passage 17, the carbon dioxide forces the tubular member 9 outwardly (Figure 3) to engage and seal with base 6 until the pressure in the tubular member and in the core box has equalized. At the same time, some of the carbon dioxide escapes through the apertures 24, permeating the sand whereby the sodium silicate sets up in a matter of seconds and the compacted form of the core is maintained permanently. The pressure on the tubular member is then released whereupon it collapses into the position shown in Figure 4, in which position the core box and the associated core can be readily removed. Thereafter, the core can be removed from the core box which is then ready for reuse.

From the foregoing, I believe it will be apparent that I have provided a novel, simple and improved form of method and apparatus for the formation of cores, particularly enabling cores to be formed with great rapidity and at low cost.

I claim:

1. The method of forming a core comprising introducing a silicate-wet molding sand between a non-yielding core box and a flexible member provided substantially centrally of the core box and closed at one end, the flexible member being perforated to pass a gas into the core box when said flexible member is distended to substantially its maximum extent, and introducing carbon dioxide under pressure to expand the flexible member and press the molding sand forcefully into the core box while simultaneously carbon dioxide passes through the perforated flexible member into the silicate-wet sand whereby the silicate reacts with the carbon dioxide and sets up firmly in the core box.

2. The method of forming a core comprising introducing a hardening agent-wet molding sand between a nonyielding core box and a flexible member provided substantially centrally of the core box and closed at one end, the flexible member being perforated to pass a gas into the core box when said flexible member is distended to substantially its maximum extent, and introducing a gas under pressure to expand the flexible member and press the molding sand forcefully into the core box while simultaneously the gas passes through the perforated flexible member into the hardening agent-wet sand whereby the agent reacts with the gas and sets up firmly in the core box.

3. Apparatus for making cores comprising a base, a flexible member closed at one end and having its open end mounted on the base, a core box mounted on the base and surrounding the flexible member in a spaced relationship to provide a space for filling with a core sand, the flexible member having a gas outlet into the core sand filling said space, said gas outlet comprising perforations sufficiently small that gas will not pass therethrough until said flexible member is distended to substantially its maximum extent by the application of gas pressure to the interior thereof, and means for supplying a gas under pressure to expand said flexible member and force gas therefrom into said space.

4-. Apparatus for making cores comprising a base, a flexible member closed at one end and having its open end mounted on the base, a seal between the flexible member and the base effective to seal the member on the base upon application of a gas pressure, a core box mounted on the base and surrounding the flexible member in a spaced relationship to provide a space for filling 4 with a core sand, the flexible member having a gas out- 2,517,902 Luebkeman Aug. 8, 1950 let into the core sand filling said space, said gas outlet 2,698,976 Toccone Ian. 11, 1955 comprising perforations sufficiently small that gas will not pass therethrough until said flexible member is dis- GN PATENTS tended to substantially its maximum extent by the ap- 5 7101099 Great Bntam June 1954 plication of gas pressure to the interior thereof, and OTHER REFERENCES means for supplying a gas under pressure to expand said flexible member and force gas therefrom into said space. 525 52 ggggi gg (pubhcanon) May 1955' References Cited in the file of this patent 10 UNITED STATES PATENTS 1,226,470 Coolidge May 15, 1917 

